封装SqliteHelper类--Sqlite数据库

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Configuration;
using System.Data.SQLite;
using System.Data;

namespace _01复习1
{
    public static class SqliteHelper
    {
        //从配置文本中读取连接字符串
        private static string connStr = ConfigurationManager.ConnectionStrings["itcastCater"].ConnectionString;

        //执行命令的方法：insert,update,delete
        //params：可变参数，目的是省略了手动构造数组的过程，直接指定对象，编译器会帮助我们构造数组，并将对象加入数组中，传递过来
        public static int ExecuteNonQuery(string sql, params SQLiteParameter[] ps)
        {
            //创建连接对象
            using (SQLiteConnection conn = new SQLiteConnection(connStr))
            {
                //创建命令对象
                SQLiteCommand cmd = new SQLiteCommand(sql, conn);
                //添加参数
                cmd.Parameters.AddRange(ps);
                //打开连接
                conn.Open();
                //执行命令，并返回受影响的行数
                return cmd.ExecuteNonQuery();
            }
        }

        //获取首行首列值的方法
        public static object ExecuteScalar(string sql, params SQLiteParameter[] ps)
        {
            using (SQLiteConnection conn = new SQLiteConnection(connStr))
            {
                SQLiteCommand cmd = new SQLiteCommand(sql, conn);
                cmd.Parameters.AddRange(ps);

                conn.Open();
                //执行命令，获取查询结果中的首行首列的值，返回
                return cmd.ExecuteScalar();
            }
        }

        //获取结果集
        public static DataTable GetDataTable(string sql, params SQLiteParameter[] ps)
        {
            using (SQLiteConnection conn = new SQLiteConnection(connStr))
            {
                //构造适配器对象
                SQLiteDataAdapter adapter = new SQLiteDataAdapter(sql, conn);
                //构造数据表，用于接收查询结果
                DataTable dt = new DataTable();
                //添加参数
                adapter.SelectCommand.Parameters.AddRange(ps);
                //执行结果
                adapter.Fill(dt);
                return dt;
            }
        }
    }
}